Industrial gas separations require large, and costly, amounts of membrane in order to carry out the necessary processes. To perform such separations, hundreds to thousands of square meters of membrane are packaged into membrane modules. The development of different technologies for efficiently packing membranes into modules at a low cost has been ongoing since the 1960s.
Current module designs include plate-and-frame and spiral-wound modules for flat-sheet membranes, and potted hollow-fiber designs for polymeric hollow-fiber membranes. Tubular modules are used for tubular membrane configurations, including ceramic tubular membranes as described herein.
U.S. Pat. No. 7,404,843, to Kaschemekat et al. (Membrane Technology and Research, Inc.), discloses one design for housing membranes, including tubular membranes, within an assembly. The assembly contains a plurality of tubes, each housing membrane modules. The tubes are supported by a tube sheet place at one end of the assembly (the feed end) and another tube sheet at the opposite end (the permeate end). A feed gas enters the assembly via a feed port and flows through the feed end tube sheet and into the membrane modules. A permeate gas which has permeated the membrane is collected in a permeate pipe that extends beyond the permeate end tube sheet and allows the permeate gas to exit the assembly via a permeate port. A residue gas flows out of the tubes through openings found on each tube and eventually out of the assembly via a residue port.
Another design for housing tubular membranes within a module is described in U.S. Pat. No. 6,790,350, to Pex et al. (Stichting Energieonderzoek Centrum Nederland). Here, the tubular membranes are housed within larger diameter tubes and are arranged adjacent and parallel to one another. Individual membranes may be in series or two pairs in parallel with the pairs being arranged in series. While this design provides for an optimized feed flow, it is limited by its serial configuration of tubes.
Despite these designs, there remains a need for an improved gas separation module for housing ceramic tubular membranes that permits parallel flow to all membranes, allows for a sweep gas to be introduced or a second permeate stream to be withdrawn from it, is inexpensive to manufacture, and provides for easy replacement of modules within an overall assembly.